000367

51 • на верхушке, • дно гайморовой пазухи, • над корнями моляров, • при удалении зубов, • соединение тела и ветви, • угол нижней челюсти, • прикрепленные к ветви, • два отростка (выступа), • вращательные движения. b) Find in the text sentences in which the Passive Voice is used. The Jaws The upper jaw is called the maxilla and the lower is called the mandible. The maxilla is fxed to the skull and is immovable. Its outer layer of compact bone is much thinner than that of the mandible. The hard palate is a part of the maxilla and forms the roof of the mouth. It separates the oral cavity from the nasal cavity. On either side of the nasal cavity the maxilla is hollow. Each hollow is known as a maxillary sinus or antrum. It is of great practical importance as the floor of the antrum lies just above the roots  1 of the premolars and molar teeth. During extraction of these teeth, the floor may be perforated or a root pushed inside the antrum. As the antrum is an air space it gives resonance to the voice. The mandible is shaped like a horseshoe [‘h ɔ :∫∫u:] with its ends bent up at right angles. The part bearing teeth is called the body of the man‑ dible and each vertical end of the horseshoe is called a ramus. The junction of body and ramus is called the angle of the mandible. Attached to the ramus are the muscles of mastication which close the mouth. Muscles opening the mouth are attached to the body just below the chin. On top of the ramus are two projections: the coronoid process in front and the condyle behind. The condyle and base of the skull form the tem‑ poromandibular joint, which allows the lower jaw to move. Chewing  2 is brought about by rotary movements of the mandible which swings from side to side, crushing food between the cusps of opposing mo‑ lars and premolars. All these movements of the jaws are produced by the muscles of mastication. Notes 1 root [ru:t] n корень 2 chewing [ ’ t∫u:iŋ] n жевание